Electrical connector for printed circuit cards



Jan. 29, 1963 FIG. I

FIG. 2'

INVENTOR. FRANKLIN RAD D! N ATTORNEY F. RADDIN 3,076,166

United States Patent Machine Company, Orange, NJ., a corporation ofDelaware Original application Dec. 13, 1956, Ser. No. 628,034, nowPatent No. 2,956,258, datedOct. 11, 1960. Divided and this applicationSept. 30, 1960, Ser. No. 59,668 3 Claims. (Cl. 339-17) This invention,which is a division of copending patent application 628,034, filedDecember 13, 1956, now Patent 2,956,258, dated October. 11, 1960, byFranklin Raddin, relates to electrical connectors for printed circuitcards or the like.

It is well known that prin'tedcircuit cards provide a number ofadvantages when used in electronic apparatus. Such cards are especiallysuited to mass production and make possible a reduction in the size ofelectronic apparatus. They also provide a modular type of constructionin electronic equipments that simplifies the maintenance problem bypermitting a quick substitution of small units which become defective.

To provide for easy replacement, the printed circuit cards normallyinclude multi-contact plugs which enter into sockets in a chassis orinter-connection unit. The making of soldered connections to the ends ofthe plug adds to the cost of construction and such plugs have a numberof disadvantages as a means for making connections to printed circuitcards, especially when the cards are miniaturized. 1

The plugs require an appreciable mechanical force on each pin to insurea reliable contact resistant to corrosion, vibration, and shock. As manycontacts are normally required, the force necessary for insertion andremoval of a card is considerable. Equipments using printed circuitcards are normally com act so that it is frequently diflicult to applyan appreciable force to remove and insert the cards. v a

In any event, the plugs limit the degree ofminiaturization which can beobtained. The card must be large enough to withstand the forces appliedto it for insertion and removal. The pin size and spacing necessary forthe plug is another limiting factor on the size of the card.

The apparatus of the instant invention provides a means for makingreliable connections directly to the printed terminals along the edgesof printed circuit cards. The spacing of the printed terminals may bethe same as the spacing of other printed conductors. Substantially zeroforce is required to insert and remove the cards so that they need to beonly strong enough to support the printed circuitry and other circuitcomponents.

In the apparatus of the instant invention, a fluid pres- I sure isapplied uniformly along rows of mating contacts to hold them togetherwith suflicient force to insure connections resistant to corrosion,vibration, and shock. At least one of the cards or other membersupporting sets of contacts is flexible and the fluid pressure means isCD111 formable in shapeso that a substantially uniform pressure will beapplied to each pair of mating contacts despite small dimensionalvariations in the contacts or their supporting members. The fluidpressure is removed to allow insertion and removal with-out wear andundesira-ble mechanical stress.

An object of the invention is an improved means of making connections toprinted circuit cards.

A further object of the invention is apparatus for making connectionsdirectly to printed terminals on printed circuit cards wherein a uniformcontact pressure is maintained with each terminal.

A still further object of this invention is apparatus for 3,676,166Patented Jan; 29, 163

. making connections to printed circuit cards from which the cards maybe inserted and removed with the application of substantially zeroforce.

Other objects and advantages together with 'a fuller understanding ofthe invention, will be had by referring to the following description andclaims taken in conjunction with the accompanying drawings in which:

PEG. 1 is a perspective view of one embodiment of the invention having asection cut away to show the internal structure.

FIG. 2 is an elevation view of a vertical section of the embodiment ofFIG. 1 taken along the line a-a.

' Notched member ,11 joins to bar 12 by screws (not shown) or by anyother suitable means, so that the two form a vertical slot runninglongitudinally. Printed circuit card 13a is inserted in the slot fromthe upper side and printed circuit card 13b from the lower side so thatportions thereof overlap each other in the slot. Member 11 is made of arigid material and has a chamber hollowed out with an opening along theside of the slot. Fluid filled flexible bag 14 is mounted inside thechamber with a side adjacent to the slot. Screw 15 journeys through athreaded hole in one end of member 11 and extends inside the chamber.Plate 16 rotatably joins to the end of screw 15 inside the chamber.

When screw 15 is turned inwardly, it forces plate 16 against fluidfilled bag 14. The fluid inside bag 14 is substantially incompressibleso that the longitudinal compression causes the bag 14 to expandlaterally into the side of the slot and to press cards 13a and 1315together against bar 12. Bag 14 is flexible so that it conforms to theshape of printed circuit card 13b allowing pressure to be applieduniformly along the portion adjacent to the chamber opening. As the areaof plate 16 is smaller than that of the portions of cards 13a and 13b inthe slot, the force exerted on the cards 13a and 13b is considerablygreater than on plate 16. Screw 15 provides a further mechanicaladvantage for manualradjus-tment.

Printed circuit cards 13a and 1312 each have a plurality of printedconductors 17 extending along the overlapping sections of theiradjoining sides. Printed conductors 17 on cards 13a and 13b are inmating relation so that each conductor 17 on card 13a makes contact witha corresponding conductor 17 on card 13b when cards 13a and 13b arepressed together. Cards 13a and 13b are sufliciently flexible to bendunder the pressure exerted through bag 14.

This flexibility of cards 13a and 1312 makes it possible to hold eachmating pair of conductors 17 together with substantially the samepressure despite small dimensional irregularities in thickness. Since noclose tolerances are required, cards 13a and 13b may be manufactured bylow cost methods. suitable type and have any arrangement of printedcircuitry and other components.

It will further be recognized that various other arrangements could alsobe used for obtaining fluid pressure in the invention other than thatshown. For example, a cam type mechanism positioned by alever could beused instead of a screw to move a plate against the bag. Such amechanism would permit quick application and removal of pressure butwould require an additional adjusting means to obtain the desiredpressure in the event of changes in dimensions of the chamber inwhichthe bag is located or of the cards and connectors use While theinvention has been described with a certain degree of particularity, itis understood that the present disclosure has been made only by way ofexample, and that numerous changes in the details of constructionwherein a combination and arrangement of parts may be resorted towithout departing from the spirit and scope of the invention ashereinafter claimed.

Cards 13a and 13b maybe of any What is claimed is:

1. An electrical connector comprising a housing having a substantiallylinear slot, a closed flexible bag filled with a substantiallyincompressible fluid mounted in said housing with a first wall thereofcoextensive with one side of said slot, two conductor carrying cardmembers of insulating material having conducting material selectivelyprinted thereon, at least one of said cards being flexible, and meansfor exerting a force on said bag whereby said abutting conductors arepressed together by movement of said first wall'of said bag.

2. An electrical connector comprising a housing having a slot, a closedflexible bag filled with a substantially incompresible fluid mounted insaid housing with at least one wall of the bag coextensive with one sideof said slot, at least two conductor carrying card members of insulatingmaterial having conducting material selectively placed theron andadapted to fit in said slot with conductors thereon in abuttingrelation, and movable plate means for exerting a force on said bagwhereby said abutting conductors arepressed together under uniformpressure by expanding movement of the wall of said bag.

3. An electrical connector comprising a housing having a slot, a closedchamber mounted in said housing having a flexible wall substantiallycoextensive with one side of said slot and filled with a substantiallyincompressible fluid, means for exerting a force on said chamber to movethe said flexible wall with respect to said slot, two conductor carryingmembers adapted to fit in said slot with the conductors abutting whereinsaid abutting conductors are pressed together by movement of saidflexible wall into said slot, said abutting sections comprisingelectrical conductors mounted in mating relation on the overlappingsections of said members.

References Cited in the file of this patent UNITED STATES PATENTS

1. AN ELECTRICAL CONNECTOR COMPRISING A HOUSING HAVING A SUBSTANTIALLYLINEAR SLOT, A CLOSED FLEXIBLE BAG FILLED WITH A SUBSTANTIALLYINCOMPRESSIBLE FLUID MOUNTED IN SAID HOUSING WITH A FIRST WALL THEREOFCOEXTENSIVE WITH ONE SIDE OF SAID SLOT, TWO CONDUCTOR CARRYING CARDMEMBERS OF INSULATING MATERIAL HAVING CONDUCTING MATERIAL SELECTIVELYPRINTED THEREON, AT LEAST ONE OF SAID CARDS BEING FLEXIBLE, AND MEANSFOR EXERTING A FORCE ON SAID BAG WHEREBY SAID ABUTTING CONDUCTORS AREPRESSED TOGETHER BY MOVEMENT OF SAID FIRST WALL OF SAID BAG.